将 JavaScript 正则表达式转换为 Swift 正则表达式 [英] Convert a JavaScript Regex to a Swift Regex

问题描述

我正在学习 Swift，并且正在尝试将一小段 JavaScript 代码转换为 Swift.JavaScript 代码使用 Regex 拆分字符串，如下所示:

I'm learning Swift, and I'm trying to convert a small bit of JavaScript code to Swift. The JavaScript code uses a Regex to split up a string, as shown below:

var text = "blah.clah##something_else";
var parts = text.match(/(^.*?)\#\#(.+$)/);

执行后，parts 数组将包含以下内容:

after execution, the parts array will then contain the following:

["blah.clah##something_else", "blah.clah", "something_else"]

我想在 Swift 中复制相同的行为.下面是我编写的使用正则表达式将字符串拆分为字符串数组的 Swift 代码:

I would like to replicate the same behavior in Swift. Below is the Swift code I've written to do split up a String into a String array using a Regex:

func matchesForRegexInText(regex: String!, text: String!) -> [String] {
do {
    let regex = try NSRegularExpression(pattern: regex, options: NSRegularExpressionOptions.CaseInsensitive)
    let nsString = text as NSString
    let results = regex.matchesInString(text,
        options: NSMatchingOptions.ReportCompletion , range: NSMakeRange(0, nsString.length))
        as [NSTextCheckingResult]
    return results.map({
        nsString.substringWithRange($0.range)
    })
} catch {
    print("exception")
    return [""]
}

}

当我使用以下命令调用上述函数时:

When I call the above function with the following:

matchesForRegexInText("(^.*?)\\#\\#(.+$)", text: "blah.clah##something_else")

我得到以下信息:

["blah.clah##something_else"]

我尝试了许多不同的正则表达式，但都没有成功.Regex (^.*?)\#\#(.+$) 是否正确，或者matchesForRegexInText() 函数有问题?我很感激任何见解.

I've tried a number of different Regex's without success. Is the Regex (^.*?)\#\#(.+$) correct, or is there a problem with the matchesForRegexInText() function? I appreciate any insight.

我使用的是 Swift 2 和 Xcode 7.0 测试版 (7A120f)

I'm using Swift 2, and Xcode Version 7.0 beta (7A120f)

推荐答案

正如评论中已经提到的，您的模式匹配整个字符串，所以 regex.matchesInString() 返回一个NSTextCheckingResult 其 range 描述了整个字符串.您要查找的是与 捕获组 匹配的子字符串在你的模式中.这些可以作为 rangeAtIndex(i) 使用，i >= 1:

As already mentioned in a comment, your pattern matches the entire string, so regex.matchesInString() returns a single NSTextCheckingResult whose range describes the entire string. What you are looking for are the substrings matching the capture groups in your pattern. These are available as rangeAtIndex(i) with i >= 1:

func matchesForRegexInText(regex: String!, text: String!) -> [String] {

    do {
        let regex = try NSRegularExpression(pattern: regex, options: [])
        let nsString = text as NSString
        guard let result = regex.firstMatchInString(text, options: [], range: NSMakeRange(0, nsString.length)) else {
            return [] // pattern does not match the string
        }
        return (1 ..< result.numberOfRanges).map {
            nsString.substringWithRange(result.rangeAtIndex($0))
        }
    } catch let error as NSError {
        print("invalid regex: \(error.localizedDescription)")
        return []
    }
}

示例:

let matches = matchesForRegexInText("(^.*?)##(.+$)", text: "blah.clah##something_else")
print(matches)
// [blah.clah, something_else]

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